Hydraulic control system



' Aug. 19, 1941.

- J. B. A, DE BOYSSON HYDRAULIC CONTROL SYSTEM Filed May 24, 1939 Patented Aug. 19, 1941 HYDRAULIC CONTROL SYSTEM Joseph Bernard Antoine de Boysson, Boulogne- Billancourt, France Application May 24, 1939, Serial No. 275,570 In France November 25, 1938 Claims.

This invention relates to a hydraulic control system particularly though not necessarily adapted for the actuation of landing gears for aircraft and the like.

use of the weight of the gear which has been previously drawn up for lowering it, the action of the weight being aided or completed if necessary by elastic means, springs or the like. Such systems, while solving the problem, have disadvantages and more particularly that of requiring, for the execution of the first operation (the drawing up) the intervention not only of forces which are suflicient for drawing up the gear but also of complementary forces for producing the bending of the elastic devices which are used. I

According to the invention the energy which is required for the second operation is accumulated in advance and the execution of the first operation is allowed only when this accumulationis achieved. It is thus possible to actuate means which have either by themselves or through additional elastic means no tendency to assume one position or the other, that is to say means which are sufficiently balanced in order that the'energies w ich are to be put in action in the course of the operations are smallyin every case, it is not necessary to overcome in the course of the first operation (the drawing up) the antagonist action of the energy which will be ulteriorly necessary for effectuating the second operation (lowering).

.The system according to the invention is characterized by an energy storage device which is insertedbetween the source of power and the means forapplying this power which must successively effectuate two or more operations, thus corresponding to a quantity of fluid which is sufficient for the execution of the second operation, this second operation being supplied without any return valve in order that the whole quantity of the stored up fluid may be used.

In the appended drawing, which shows by way of example devices for the carrying into practice of the system according to the invention:

Figure l is a diagram showing a first form of. execution applied to the drawing up of the landing gear of an aircraft.

Figure 1a shows a second position of the distributor of Figure 1.

Figure 2 is a diagrammatical view of another embodiment or difierent combination of connections.

Figure 2a shows a second position of the distributing valve of Figure 2. V

Figure 3 shows another form of execution for the control of various organs.

Figure 4 shows another form of execution applicable instead of one of the preceding forms of executions.

not permitting the execution of the first 'operation before sufficient-energy for effectuating the succeeding operations has not been stored'up'.

To this end, preferably, a double acting hydraulic accumulator will be used which preferably comprises a single body and in which a return valve controlled by the piston allows of the feeding of the device for the first operation only Figure 5 shows the particular arrangement of a rod 9 provided with a head Ill for facilitating the actuation of the rod by the piston 5 rests on its seat ll so long as the piston 5 has not risen sufliciently high for engaging the head III. This results in the line I2 not being supplied with fluid so long as a sufficient quantity of fluid has not, been introduced into the accumulator. Another line l3 freely communicates with the chamher 1.

The landing gear I! to be actuated rocks about theshaft IS in order to come to the retracted position Ha under the action of a double acting jack I6 provided with a piston I! the rod [8 of which actuates the gear l4. The front chamber IQ of the jack is directly supplied with fluid by the line l3. The back chamber 20 is connected by a pipe 22- to a distributing valve 2| which insures, at will, the connection of this pipe 22 with the line l2 (see Figure l) orwith the line 24 space occupied and the least weight of the accumulator.

the use of a pump working automatically, since the first action of the pump when put in opera- 8, the distributing valve 2| assuming the. posi- I tion shownin Figure 1, the pressure is exerted on both faces of the piston I! of the jack "5 and the piston rod l8 efiects the outward stroke corresponding to the first operation.

If the accumulator is not sulficiently filled, the piston 5 when moving downwardly owing to the consumption of fluid will permit of the valve 8 dropping onto its seat again and the movement of the gear will be stopped before the first operation has been achieved. It will continue only so far as the pump I will deliver the necessary fluid.

If the filling of the accumulator is too deficient, the initial position of the piston 5 will not even permit of. the movement corresponding to the first operation to begin.

In order to obtain the shifting of the gear from Mo to M it is suflicient to bring the distributing-valve 2| to the position of Figure 1a and the pressure in the front chamber I19 of the jack will produce the desired movement.

Figure 2 shows a difierent position of the jack and a different combination of the distributing valve. The drawing up of the gear 35 being obtained through an action on the annular chamber 32 of the jack 30, the distributing valve 23 is brought to theposition of Figure 2a in which the lines 28 and 29 respectively, put the front annular chamber 32 of the jack 30 into communication with the pressure of the chamber I through the line I2 and the valve 8 and II, and

the rear chamber 3| of the jack 30 into communication with the drain pipe 24.

In .order to lower the'train, the distributing valve 23 is brought to .the position of Figure 2 in which both chambers 3| and 32 are put' into free communication with the chamber 1 of the accumulator 4.

The lowering of the gear is obtained through a difierential action of the chambers 3| and 32 of the jack 30 which are both under pressure and drive out the rod 34 of the piston 33. I

The organs tobe actuated can be otherorgans than landing gears of aircraft.

' The arrangements of the operating jacks, the

valve which is also actuated by the piston, the

arrangement being such that the actuated] valves may be opened at different pressures without de-' parting from the scope of the present invention.

The capacity of the accumulator may either correspond to the whole of the actuating operations which are foreseen for a rather long period of time, the pump serving only for re-charging, or correspond only to the operation which it is desired to offer the possibility of beingefiected tion for producing the first action will be sufficient to charge the accumulator.

Figure 3 shows an example of an arrangement I of this kind in which the controlled line |2a suppl-ies a series of operating distributing valves 31,

31a, 31b and so on with fiuid, the free line l3 serving only for the safety operation of the reserved organ.

It is also possible to control the insulating valve through another; organ than the piston of the accumulator itself, which; in certain cases, may facilitate the mounting of the system or. reduce 'the space which it occupies. Figure 4 shows an arrangement of this kind. The main accumulator 38 is supplied with fluid through 3 and communicates freely with the free line l3. A line connects the chamber 40 with the lower chamber of the auxiliary accumulator 43 which controls through its piston 42 the raising or closing movement of the valve 4| with the shaft 46; the stroke of the piston 42 can be limited by stops 44, 44a so as to have a very small size for the controlled valve device the own dimensions of which thus become independent of the capacity of the main accumulator. Any other manometric device of a known type can also be used in connection with an accumulator having an elastic charge.-

Furthermore, in the case when the energy which is necessary for the other operations than the reserved operation is directly supplied by the pump, it can be advantageous to provide a device which permits of effecting the operations sup- .plied by the pump at "a pressure which is lower in every case, the other operations being effected only throughthe deliveryof the pump, which may reach the operation line l2 only so far as the accumulator is tity of fluid. v

This latter operation provides for the safety storage before any other operation, this storage being thus obtained at the expense of the least filled with a suitable quanthan the pressure which is necessary for constituting the accumulated storage. In fact; in the absence of a suitable device, as 'soon as the valve 8 .is unseated, if the resisting pressure in the line 2 is smaller than the pressure in the chamber 1 of the accumulator, this latter tends to be emptied into the line |2, which closes the valve 8 again, this valve being then raised againby the delivery of the pump, thus causing a series of beats and of hydraulic shocks which have a prejudicial action.

In this case a system such as the system represented in Figure 5 can be'used.

The chamber 1 of theraccumulator 4 is closed in its lower part by a partition 41 so as to separate an auxiliary chamber 50. The rod 3 of the valve 8 passes through the partition through an opening provided with a gasket 49. The line 3 which supplies the device or the devices for which the energy has been stored up opens into the upper part of the chamber I; the line leading to the pump opens into the auxiliary chamber 50. A return valve 48 (which can be used instead of the valve- 3 of Figure 1) permits the communication in a single direction between the chambers 50 and 1. g

It can be'seen that with this arrangement the reserve chamber 1 cannot tend to empty itself into the line I2 when the valve 8 is opened In this case it is possible to avoid' I which is exerted on the piston 5 is increased by the value of the released charge, which causes an unhindered unseating.

The invention can be used for the actuation of the landing gear or of any other parts of aircraft and generally in all the cases when it is desired to efiectuate the controlof parts through the medium of servo-motors.

What I claim is: 1

1. A hydraulic control system of the character described, comprising a reciprocable double acting hydraulic jack, a fluid pressure generator for said jack, an energy storage device in communication with said pressure generator, a conduit establishing communication between said energy storage device and one side of said jack, a second conduit establishing communication between said storage device and the other side of said hydraulic jack, valve means in said second conduit, means responsive to the pressure in said energy storage device for controlling the operation of said valve means, whereby the operation of said hydraulic jack is dependent upon the pressure in said storage device, and second valve means in at least one of said conduits for controlling the admission to and exhaust of fluid from said jack.

2. A hydraulic control system of the character described, comprising a reciprocable double acting hydraulic jack, a fluid pressure generator for said jack, an energy storage device in communication with said pressure generator, a conduit establishing communication between said energy storage device and one side of said jack, a. second conduit establishing communication between said storage device and the other side of said hydraulic jack, valve means in said second conduit, a reciprocable piston operatively connected to said valve means and responsive to the pressure in said storage device, whereby the operation of said jack'is dependent upon the pressure in said storage device, and hand operated valve means in at least one of said conduits for controlling the admission to and exhaust of fluid from said jack.

3. A hydraulic control system of the character described, comprising a reciprocable double acting hydraulic jack, a fluid pressure generator for said jack, an energy storage device in comthe flowvof fluid pressure from said storage device to said jack, means operatively connected to said valve and responsive to the pressure of fluid in said storage device sufficient to effect all of the operations of said hydraulic jack, for opening said valve means to effect the first operation of said jack, and hand operated valve means for controlling the admission of fluid pressure to and the exhaust of fluid pressure from said jack.

4. Apparatus as claimed in claim 3 wherein said pressure responsive means comprises a piston reciprocatable in said storage device.

5. Apparatus as claimed in claim 3 wherein the fluid chamber of said energy storage device is divided into an upstream compartment and a down-stream compartment separated by a single partition provided with a check valve for the communication between said compartments in one direction, said second named conduit being in communication with said upstream compartment, and said pressure responsive means and said first named conduit being in communication with said down-stream compartment.

JOSEPH BERNARD ANTOINE DE BOYSSON. 

